glucose tolerance test


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glu·cose tol·er·ance test (GTT),

a test for diabetes, or for hypoglycemic states such as may be seen, rarely, in patients with insulinomas. Following ingestion of 75-g glucose while the patient is fasting, the blood sugar promptly rises and then falls to normal within 2 hours; in diabetic patients, the increase is greater and the return to normal unusually prolonged; in hypoglycemic patients, depressed glucose levels may be observed in 3-, 4-, or 5-hour measurements.

glucose tolerance test (GTT)

a test of the body's ability to metabolize carbohydrates by administering a standard dose of glucose and measuring the blood and urine for glucose level at regular intervals thereafter. The patient usually eats a high-carbohydrate diet for the 3 days before the test and fasts the night before. A fasting blood glucose level is obtained the next morning, and then the patient drinks a dose of glucose based on his or her weight. Blood and urine are collected periodically for up to 6 hours. The glucose tolerance test is most often used to assist in the diagnosis of diabetes, hypoglycemia, or other disorders that affect carbohydrate metabolism.

glucose tolerance test

A standardized test that measures the body's response to an oral–challenge dose of glucose, which is primarily used to confirm the diagnosis of DM, and may be performed in individuals with symptoms–eg ↑ fasting glucose level, hypertriglycerdemia, neuropathy, impotence, glycosuria that are suggestive of DM; in pregnancy GTT is used to diagnose gestational DM

glu·cose tol·er·ance test

(GTT) (glū'kōs tol'ĕr-ăns test)
A test for diabetes, or for hypoglycemic states such as may be seen rarely in patients with insulinomas. Following ingestion of 75 g of glucose while the patient is fasting, the blood sugar promptly rises and then falls to normal within 2 hours; in diabetic patients, the increase is greater and the return to normal unusually prolonged; in hypoglycemic patients, depressed glucose levels may be observed in 3-, 4-, or 5-hour measurements.

glucose tolerance test

A test of the body's response to a dose of glucose after a period of fasting. The blood sugar levels are measured at various intervals after the sugar is taken and the results plotted on a graph. A characteristic shape of the curve occurs in DIABETES because the blood sugar levels rise to an abnormal height and take longer than usual to return to normal. A urine test also shows sugar, in diabetes.

test

trial/experiment assisting diagnosis
  • Allen's test test of arterial occlusion in the foot, i.e. leg elevation (until plantar skin blanches and Doppler sound at dorsalis pedis [DP] pulse is lost) followed by compression of DP pulse (by clinician's thumb) and lowering of leg to dependency; if posterior tibial artery flow is adequate the foot rapidly resumes its normal colour; test is repeated at posterior tibial pulse, to test patency of DP

  • anterior drawer test; ADT; Lachman's test test of stability/integrity of lateral collateral ligaments of ankle joint, i.e. flex knee to >45° (to relax posterior muscle group), stabilize lower tibia (with one hand) whilst grasping posterior aspect of patient's heel (with the other); calcaneum is pulled forward as a simultaneous retrograde force is applied to lower tibia; positive ADT = > 4mm anterior displacement of foot relative to tibia together with positive 'suction sign'

  • Buerger's test test of arterial status of lower limb, i.e. patient reclines supine on couch; leg is elevated (from hip) for 1 minute (whilst patient alternately dorsi- and plantarflexes ankle joint, to drain venous circulation); limb is lowered to dependency or patient stands up (foot shows brief hyperaemia before returning to normal skin colour); time (in seconds) for normal colour return is noted; >20 seconds = inadequate arterial supply; >40 seconds = severe limb ischaemia; note: clinician should note whether cyanosis (rather than brief hyperaemia) occurs on dependency, and duration of cyanosis; persistent dusky red/purple coloration in dependent limb that appears to resolve to normal skin tone on raising limb to horizontal indicates severe arterial compromise

  • Clarke's test diagnostic test of chondromalcia patellae; with the patient supine and the affected knee fully extended, the clinician applies gentle pressure to the patella whilst the patient attempts to contract the quadriceps muscle group; the test is positive if severe patellar pain occurs

  • Coombs test test to predict donor and receiver blood compatibility, i.e. assay for presence/absence of specific antibodies on donor erythrocytes

  • coordination tests tests of cerebellar coordination of lower-limb motor function, i.e. heel-shin test; fingertip test

  • fingertip test test of cerebellar function, i.e. patient repeatedly attempts to place his/her fingertip on tip of assessor's moving finger; alternatively, patient attempts to put tip of his/her index finger alternately on his/her nose then on assessor's moving finger

  • glass test test for meningitis, i.e. test is positive when there is no blanching of a pruritic rash when it is pressed with a glass

  • glucose tolerance test; GTT diagnostic test of diabetes mellitus, and assessment of patients with fasting blood glucose levels just above normal range (i.e. 5.6-6.7 mmol/L), i.e. 75mg glucose is given (as a drink) after starving for 12-14 hours; its rate of blood clearance is monitored over the next 3 hours; in normal patients, there is an immediate and sharp rise in blood glucose which falls during subsequent 2 hours to normal glycaemic levels (i.e. 2.9-5.9 mmol/L); in diabetes/insulin resistance cases, blood glucose levels rise initially to a higher level and do not return to normal range within 2 hours

  • Heaf test test of immunity to tubercle bacillus (tuberculosis [TB]), i.e. subdermal injection of attenuated tuberculin toxin

  • heel-shin test test of cerebellar function, i.e. patient repeatedly places one heel on anterior aspect of other shin and slides heel down to dorsum of foot; inability to perform this test indicates cerebellar dysfunction and other conditions characterized by loss of motor coordination

  • interdigital test reduced blunt/sharp discrimination, paraesthesia, hyper-/hypoaesthesia of interdigital skin at toe cleft affected by neuritis/Morton's neuroma

  • Jack's test passive dorsiflexion of hallux at first metatarsophalangeal joint in weight-bearing foot

  • Kelikian push-up test intraoperative check of adequate surgical correction of lesser-toe deformity, i.e. elevation of head of relevant metatarsal with thumb pressure

  • Lachman's test see test, anterior drawer

  • Mantoux test, tuberculin test screening test for exposure to tuberculosis (TB); administration of an intradermal dose of tuberculosis antigen (tuberculin) to the skin of the forearm; a localised, small, firm inflammatory skin reaction developing within 2 days shows positive exposure to tuberculosis

  • Mulder's test diagnostic test for Morton's neuroma, i.e. simultaneous lateral compression across metatarsal heads + thumb pressure at affected plantar web space in a foot with symptoms of plantar digital neuritis (Morton's neuroma); positive result (i.e. induction of characteristic symptoms of a nerve entrapment pain, and examiner's awareness of a fluid thrill [or click] within the palpated tissue) indicates neuritis or neuroma

  • Nobel's test test for iliotibial band (ITB) syndrome, i.e. palpation of lateral tibial condyle causes ITB pain

  • Ober's test test for iliotibial band (ITB) syndrome, i.e. excessive tightness/tension on palpation of the ITB

  • patch test; skin test test of hypersensitivity, i.e. application of a range of potential sensitizing agents to skin (e.g. back, ulnar aspect of arm); degree of inflammatory reaction (provoked by test agents) is compared with a control (innocuous substance) and 'read'/assessed after 48-96 hours

  • pole test test to estimate foot systolic pressures in limbs with arterial calcification, i.e. with patient supine, leg is elevated until Doppler foot pulses cease, and elevation height (in cm) from apex of hallux to bench is noted and multiplied by 7.35

  • Romberg's test test comparing amount of body sway of an erect patient with eyes closed and eyes open; test is positive if patient shows loss of balance/increased tendency to sway when standing with eyes closed

  • screening test any test that categorizes by predetermined characteristic/property

  • single-leg raise test; tiptoe test test of tendo Achilles (TA), tibialis posterior and peroneal integrity/function, i.e. patient stands on one leg and weight-bears on tiptoe; patient with TA damage will not be able to rise normally to tiptoe on affected side; with TA rupture, patient will not be able to rise up on to tiptoe on the affected limb at all; heel pain during single-leg raise is indicative of Sever's disease see sever's

  • skin test see test, patch

  • talar tilt test test of integrity of lateral collateral ligament of the ankle, calcaneofibular ligament and tibialis posterior tendon, i.e. with the ankle joint at neutral (0° dorsiflexion) the calcaneum is passively inverted by the examiner; if the lateral collateral ligament is damaged (e.g. anterior talofibular ligament rupture) excessive talar excursion occurs; tissue dimpling inferior to the lateral malleolus indicates rupture of the calcaneofibular ligament; greater than expected talar eversion and flattening of the medial longitudinal arch indicate tibialis dysfunction

  • Thompson's test test of Achilles tendon function, i.e. with the patient lying prone, the posterior calf muscle group is squeezed, causing ankle joint plantarflexion; the foot does not plantarflex in total Achilles tendon rupture

  • thumb roll test test for 'runner's knee', i.e. the knee is flexed by 30-40° and the examiner's thumb rolled across the medial aspect of the patella, causing a painful 'snap' or 'click', and detection of a fibrous ridge/'shelf' at anterior knee compartment

  • Trendelenburg's test test of the quality of venous filling time, and quality of venous drainage in the leg, i.e. carried out as Buerger's test, but the time (in seconds) taken for the dorsal foot veins to refill and the direction of blood flow into the dorsal foot veins is noted; refill from proximal to distal indicates venous backflow and vein valve incompetence

  • Tuberculin test see Mantoux test

  • urea breath test test to detect Helicobacter pylori gastritis, or confirm its eradication, i.e. by analysis of exhaled breath

  • Valsalva's test test to detect autonomic neuropathy, i.e. the patient exhales into an empty plastic syringe (the other end of which is connected to a manometer to be maintained at 40mmHg) for 10 seconds, and changes in heart rate are noted (i.e. maximum expiratory heart rate and minimum heart rate after test cessation), and compared as a ratio; ratio of <1:10 indicates autonomic neuropathy (normal = >1:21)

  • vertical stress test test of plantar plate rupture, i.e. application of vertical stress to metatarsal head; translocation (i.e. > 2mm dorsal elevation) of base of toe in relation to dorsum of metatarsal head indicates plantar plate rupture

  • vibration test test of peripheral sensory function (assessing pacinian corpuscle function), i.e. application of vibration stimuli (from activated 128Hz tuning fork or neuraesthesiometer) to bony prominences (e.g. medial aspect of first metatarsophalangeal joint, lateral aspect of fifth metatarsal styloid process, medial and lateral malleoli, tibial tuberosity); vibrational awareness is reduced in the elderly and may be lost in diabetic distal sensory neuropathy, correlating with reduced pain awareness

glu·cose tol·er·ance test

(GTT) (glū'kōs tol'ĕr-ăns test)
Assessment for diabetes or for hypoglycemic states. Following ingestion of 75-g glucose while the patient is fasting, blood sugar promptly rises and then falls to normal within 2 hours; in diabetic patients, increase is greater and return to normal unusually prolonged; in hypoglycemic patients, depressed glucose levels may be observed in 3-, 4-, or 5-hour measurements.

glucose, d-glucose

a simple sugar, a monosaccharide in certain foodstuffs, especially fruit, and in normal blood; the major source of energy for many living organisms. See also dextrose.
Glucose, whose molecular formula is C6H12O6, is the end product of carbohydrate digestion; other monosaccharides (fructose and galactose) are largely converted into glucose. Glucose is the only monosaccharide present in significant amounts in the body fluids. The oxidation of glucose produces energy for the body cells; the rate of metabolism is controlled by a number of hormones the most important of which are insulin and glucagon. Glucose that is not needed for energy is stored in the form of glycogen as a source of potential energy, readily available when needed. Most of the glycogen is stored in the liver and muscle cells. When these and other body cells are saturated with glycogen, the excess glucose is converted into fat and stored as adipose tissue. See also hypoglycemia, hyperglycemia.

[1-14C]-glucose
radioactive glucose used experimentally.
liquid glucose
a thick syrupy, sweet liquid, consisting chiefly of dextrose, with dextrins, maltose and water, obtained by incomplete hydrolysis of starch; used as a flavoring agent, as a food, and in the treatment of dehydration.
glucose-1-phosphate
an intermediate in carbohydrate metabolism.
glucose-6-phosphatase
a liver (and kidney) enzyme that irreversibly cleaves glucose-6-phosphate to free glucose and phosphate; important in glucose homeostasis.
glucose-6-phosphate
an intermediate in carbohydrate metabolism.
glucose-6-phosphate dehydrogenase (G6PD)
a regulatory enzyme in the metabolism of glucose-6-phosphate. A deficiency of the enzyme in the erythrocyte results in a hemolytic anemia; an inherited abnormality in humans, rats and mice and acquired in animals in phenothiazine toxicity and ingestion of kale.
glucose phosphate isomerase
converts glucose-6-phosphate to fructose-6-phosphate and the reverse reaction.
glucose suppression test
suppression of blood levels of growth hormone by the intravenous administration of glucose is used to diagnose acromegaly.
glucose tolerance factor (GTF)
a naturally occurring substance containing chromium which potentiates the effects of insulin.
glucose tolerance test
a test of the body's ability to utilize carbohydrates. It is often used to detect abnormalities of carbohydrate metabolism such as occur in diabetes mellitus, hypoglycemia, and liver and adrenocortical dysfunction. If administered orally, it may also be used to assess the absorptive capacity of the small intestine.
References in periodicals archive ?
O'Sullivan JB, Mahan CM: Criteria for the oral glucose tolerance test in pregnancy.
8] If there are errors to be made, laboratorians must err in the direction of running too many glucose tolerance tests and diagnosing too many patients with IGT.
The results also raise questions about optimal glucose levels in women with coronary artery disease who undergo a glucose tolerance test, wrote Dr.
It's a big barrier to get them into the system, to get them to the lab to do a formal glucose tolerance test.
He reported on 17,532 individuals who underwent an oral glucose tolerance test as part of the screening process for participation in the Nateglinide and Valsartan in Impaired Glucose Tolerance Outcomes Research (NAVIGATOR) trial.
In this retrospective cohort study; the researchers analyzed diabetes risk over a mean 9-year follow-up period in 31,000 women without gestational diabetes who had an oral glucose tolerance test (OGTT) or oral glucose challenge test (OGCT) during their pregnancy.
The data from Kaiser Permanente of Colorado include all 36,403 pregnancies among 30,216 initially nondiabetic women who delivered singleton infants from 1994 to 2002 and had been screened at 24-28 weeks by the same protocol: a 1-hour 50-g oral glucose tolerance test (OGTT), followed by a diagnostic 3-hour 100-g OGTT among those with glucose values at or above 140 mg/dL on the 50-g test.
A woman at low risk of gestational diabetes, based on a negative result from a 1-hour, 50-g glucose tolerance test, will remain at low risk during a subsequent pregnancy within the next 4 years.
Because of their increased risk of developing impaired glucose tolerance and type 2 diabetes, all women with polycystic ovary syndrome should be screened with a 2-hour oral glucose tolerance test, and that test should be repeated every 2 years, according to a statement from the Androgen Excess Society.
Of the 37 mothers who were studied, 10% had diabetes and 26% had impaired glucose tolerance to a 2-hour glucose tolerance test.
Administration of the compound led to significant reductions of the hepatic fat content (as assessed by MRI and liver biopsies), body weight, and serum liver enzyme levels as well as marked improvement of the glucose tolerance test and lipid profile.
8 mmol/L (140 mg/dL) or greater, a formal 75-g oral glucose tolerance test is done.

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